Limulus clotting enzyme (, ''clotting enzyme'') is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

. This enzyme catalyses the following

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

: Selective cleavage of -Arg¹⁸- and -Arg⁴⁷- bonds in coagulogen to form

coagulin Coagulin is a gel-forming protein of hemolymph that hinders the spread of invaders by immobilising them. It is produced in the coagulogen form before being cleaved into the active form. In human medicine, coagulation of coagulin is the basis of de ...

and fragments This enzyme is present in the

hemocyte A blood cell, also called a hematopoietic cell, hemocyte, or hematocyte, is a cell produced through hematopoiesis and found mainly in the blood. Major types of blood cells include red blood cells (erythrocytes), white blood cells (leukocytes), a ...

granules of

horseshoe crab Horseshoe crabs are marine and brackish water arthropods of the family Limulidae and the only living members of the order Xiphosura. Despite their name, they are not true crabs or crustaceans: they are chelicerates, most closely related to arachn ...

Limulus ''Limulus'' is a genus of horseshoe crab, with one extant species, the Atlantic horseshoe crab (''Limulus polyphemus''). One fossil species is currently assigned to the genus though several other species have been named, which have since been as ...

and

Tachypleus ''Tachypleus'' is a genus of south, southeast and east Asian horseshoe crabs in the family Limulidae. Species There are two extant (living) species: * ''Tachypleus gigas'' ( Müller, 1785) * ''Tachypleus tridentatus'' (Leach, 1819) And two ext ...

. In the immunity-related clotting pathways of these organisms, it is the final enzyme responsible for the activation of

References

External links

* {{Portal bar, Biology, border=no EC 3.4.21